Regular, revisited

on YouTube ↗01h 05m

" summary

Explains why regular = semi-regular + equality matters for STL algorithms, shows C++20 Concepts and three‑way comparison formalizing requirements, and gives concrete surprises: NaN breaks set/ordering semantics, and span loses operator== (so it becomes non‑regular). Demos use string_view, optional, span and sort/set examples, cites Stepanov and Winters, points to slides and survey, and argues design choices actually implemented (equality removed for span) change whether things behave intuitively.

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" chapters (12)

1. 0:00Regular types in C++
2. 1:29Why regular types matter
3. 7:13Values objects and types in C++
4. 12:58Mathematical foundations essential
5. 17:46STL design and value semantics
6. 29:18STL algorithm requirements
7. 33:42Weak ordering and sorting
8. 40:09Equality vs equivalence in C++
9. 44:51Regular and semi-regular types
10. 50:14Modern C++ features and value semantics
11. 57:04String view and non-owning types
12. 1:02:22Call to action for regular types

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